1. Field of the Invention
The invention relates to power-gating control techniques and particularly to power-gating control methods and systems applied to multi-thread programs.
2. Description of the Related Art
Power dissipation of electronic components comprises: static power dissipation and dynamic power dissipation. Static power dissipation is caused by Complementary Metal-Oxide-Semiconductor (CMOS) current leakage. Dynamic power dissipation is generated by switching transient current and charging/discharging current of load capacitors. With continued development of semiconductor processing technology, the size of transistors has reduced, the total number of functional units has increased, and static power dissipation has become more of a problem. As such, it is an important issue to reduce static power dissipation.
A common technique used to solve static power dissipation from occurring is power-gating control design, which controls the power of idle components by power-gating control instructions. The static power dissipation caused by current leakage of idle components can be dramatically reduced by the power-gating control design. The prior art of the invention comprises Taiwan patent publication No. 172459 and Taiwan patent application No. 94147221. The Taiwan publication No. 172459 discloses techniques comprising, obtaining information on the utilization of the components by data flow analysis and arranging power-off instructions prior to the idle regions of the components and power-on instructions after the idle regions of the components. By setting the idle components to a sleep mode, current leakage is reduced. To deal with cases having too much components, Taiwan application No. 94147221 discloses techniques comprising, determining whether the power-gating control instructions are mergeable by data flow analysis and arranging merged power-gating control instructions in proper places to replace the original power-gating control instructions. The merged power-gating control instructions with proper design save more power than the original power-gating control instructions.
The above mentioned techniques are applied to programs with single thread, but cannot be applied to multi-thread programs.
For example, “A conservative data flow algorithm for detecting all pairs of statements that may happen in parallel for rendezvous-based concurrent programs,” G. Naumovich and G. S. Avrunin disclosed in Proceedings of the 6th ACM SIGSOFT Symposium on the Foundations of Software Engineering, discloses that a may-happen-in-parallel region of a multi-thread program comprises a plurality of threads. The threads are executed in uncertain order so that the idle region of the component is uncertain. The techniques disclosed by Taiwan publication No. 172459 and Taiwan patent application No. 94147221, therefore, cannot be applied to multi-thread programs. Thus, power-gating control techniques for multi-thread programs are called for.